WO2024038669A1

WO2024038669A1 - Coiling machine and production method for coil springs

Info

Publication number: WO2024038669A1
Application number: PCT/JP2023/022577
Authority: WO
Inventors: 尚岩田; 将梧市川; 雄一郎山内; 怜田中
Original assignee: 日本発條株式会社
Priority date: 2022-08-15
Filing date: 2023-06-19
Publication date: 2024-02-22
Also published as: JP2024025901A

Abstract

This coiling machine comprises: a laser heater for heating a portion of a wire, which is to be formed into a spiral shape, by irradiating the same with a laser beam; and a cutting unit for cutting the portion of the wire heated by irradiation with the laser beam. The power density of the laser beam is 10-100 W/mm².<sp />

Description

Coiling machine and coil spring manufacturing method

The present invention relates to a coiling machine for manufacturing a coil spring and a method for manufacturing a coil spring.

A coil spring forming machine described in Patent Document 1, for example, is known as an apparatus for manufacturing coil springs. This coil spring forming machine calculates the position of the cutting part in advance based on the length of the wire to be spirally formed, and cuts the wire while softening the cutting part by high-frequency heating.

On the other hand, coiling machines are also known, such as the spring manufacturing apparatus described in Patent Document 2, which cut a spirally formed wire using a laser beam.

When using high frequency heating like the coil spring forming machine of Patent Document 1, the responsiveness of heating the cut portion is not good. In addition, in the coil spring forming machine, the wire is cut while the cutting region continues to be heated by high-frequency heating, so that the members used for cutting may be affected by the high-frequency heating. Furthermore, in this coil spring forming machine, the responsiveness of high-frequency heating is not sufficient and the wire is coiled while it is partially heated, so it is difficult to maintain a constant spring forming accuracy. There is a possibility that it will become difficult.

On the other hand, the spring manufacturing apparatus of Patent Document 2 requires a high-power laser beam that can cut the wire. In this case, sputtering may occur due to laser light irradiation, and the laser light may irradiate not only the wire but also various parts of the spring manufacturing apparatus, so these measures must be taken.

On the other hand, the applicant of the present application has proposed a method in which a portion of the wire heated by laser light is cut using a cutting component such as a cutter, as described in Patent Document 3. According to this method, the wire can be easily cut and a coil spring having a good cut surface can be obtained.

Japanese Unexamined Patent Publication No. 62-50028 Japanese Patent Application Publication No. 6-218476 Patent No. 7066880

As described above, there is room for various improvements in the method of cutting the portion of the wire heated by laser light using a cutting component. For example, the conditions for irradiating the wire with laser light need to be appropriately determined so that the wire is heated to a temperature suitable for cutting and the cross section of the wire after cutting has a good shape.

One of the objects of the present invention is to provide a coiling machine and a method for manufacturing a coil spring that can improve the manufacturing efficiency of coil springs and manufacture coil springs with good shapes.

The coiling machine according to the present invention includes a laser heating machine that heats a part of the wire by irradiating the wire into a spiral shape with laser light, and a coiling machine that heats a part of the wire by irradiating the wire with laser light. a cutting unit that cuts the part, and the output density of the laser beam is 10 W/mm ² or more and 100 W/mm ² or less.

Further, the method for manufacturing a coil spring according to the present invention includes heating a part of the wire by irradiating a wire formed into a spiral shape with a laser beam, and heating a part of the wire by irradiating the wire with the laser beam. cutting a portion of the wire, and the output density of the laser beam is 10 W/mm ² or more and 100 W/mm ² or less.

In each of the coiling machine and the manufacturing method, the power density is preferably 31 W/mm ² or more and 74 W/mm ² or less.

For example, the output density is a value obtained by dividing the output of the laser beam by the area of the irradiation region of the laser beam on the surface of the wire when viewed in the irradiation direction of the laser beam. Further, the irradiation area is an area defined by the half width of the output distribution of the laser beam on the surface of the wire. The irradiation area may have an elongated shape in the width direction of the wire.

In one example, the diameter of the wire is 8 mm or more and 18 mm or less, the area of the irradiation region is 16 mm ² or more and 108 mm ² or less, and the output of the laser beam is 500 W or more and 8000 W or less.

According to the present invention, it is possible to provide a coiling machine and a method for manufacturing a coil spring that can improve the manufacturing efficiency of coil springs and manufacture coil springs with good shapes.

FIG. 1 is a schematic perspective view showing main parts of a coiling machine according to an embodiment. FIG. 2 is a schematic front view of a coiling machine according to one embodiment. FIG. 3 is a flowchart showing the operation of the coiling machine according to one embodiment. FIG. 4 is a schematic perspective view showing a specific example of a spiral forming process using a coiling machine according to an embodiment. FIG. 5 is a schematic perspective view showing a specific example of a heating process performed by a coiling machine according to an embodiment. FIG. 6 is a perspective view showing a first example of a method of heating and softening a part of the wire in the heating step. FIG. 7 is a cross-sectional view of the wire along line VII-VII in FIG. FIG. 8 is a perspective view showing a second example of a method of heating and softening a part of the wire in the heating step. FIG. 9 is a cross-sectional view of the wire taken along line IX-IX in FIG. FIG. 10 is a schematic perspective view showing a specific example of a cutting process by a coiling machine according to an embodiment. FIG. 11 is a schematic cross-sectional view of a wire irradiated with laser light. FIG. 12 is a cross-sectional view showing an example of a suitable positional relationship between the cutter, the mandrel, and the laser beam irradiation area. FIG. 13 is a sectional view showing a state in which the cutter is lowered from the state shown in FIG. 12 to cut the wire. FIG. 14 is a schematic side view of a coil spring cut from wire in the manner shown in FIGS. 12 and 13. FIG. 15 is a schematic plan view of the surface of a wire that is irradiated with a laser beam having a rectangular beam profile, as viewed in the irradiation direction. FIG. 16 is a diagram for explaining the definition of the irradiation area shown in FIG. 15. FIG. 17 is a schematic plan view of the surface of a wire irradiated with a laser beam having a circular beam profile, viewed in the irradiation direction. FIG. 18 is a diagram for explaining the definition of the irradiation area shown in FIG. 17. FIG. 19 is a table showing irradiation conditions and examples that can be applied to laser light.

Hereinafter, embodiments related to a coiling machine and a method for manufacturing a coil spring will be described with reference to the drawings.

FIG. 1 is a schematic perspective view showing the main parts of a coiling machine 100 according to the present embodiment. FIG. 2 is a schematic front view of the coiling machine 100 shown in FIG. 1. As shown in FIGS. 1 and 2, a conveying direction X, a vertical direction Y, a forming direction Z, and a circumferential direction Dθ are defined. The conveying direction X, the vertical direction Y, and the forming direction Z are orthogonal to each other. The conveyance direction X is the direction in which the straight wire 1 before being formed into a spiral shape is conveyed. The forming direction Z is the direction in which the coil spring made of the spirally bent wire 1 extends (the direction in which the coil spring grows). The circumferential direction Dθ is the direction in which the wire 1 constituting the coil spring is wound.

The coiling machine 100 includes a conveying unit 10, a spiral forming unit 20, a heating unit (laser heating machine 30), a cutting unit 40, and a control unit 50.

In the example shown in FIGS. 1 and 2, the transport unit 10 includes a pair of drive rollers 11, a pair of driven rollers 12, and a wire guide 13. The transport unit 10 may include more drive rollers 11 and more driven rollers 12.

Each driving roller 11 and each driven roller 12 are opposed to each other via the wire 1. When each driving roller 11 rotates, each driven roller 12 rotates via the wire 1. With this rotation, the wire 1 sandwiched between each drive roller 11 and each driven roller 12 is transported in the transport direction X. The wire 1 is inserted into the wire guide 13. The wire guide 13 guides the wire 1 so as to move straight in the conveying direction X, and leads the wire 1 to the spiral forming unit 20 .

The spiral forming unit 20 forms the wire 1 transported by the transport unit 10 into a spiral shape. In the example of FIGS. 1 and 2, the spiral forming unit 20 includes a first forming roller 21, a second forming roller 22, and a pitch tool 23.

The first forming roller 21, the second forming roller 22, and the pitch tool 23 are arranged in order along the circumferential direction Dθ. The positions of the first forming roller 21, the second forming roller 22, and the pitch tool 23 in the forming direction Z are different from each other.

The first forming roller 21 and the second forming roller 22 sequentially bend the wire 1 conveyed in the conveying direction X in the vertical direction Y. The wire 1 sequentially bent in this manner draws an arc along the circumferential direction Dθ. The bent wire 1 is guided by the pitch tool 23 at a position shifted from the second forming roller 22 in the forming direction Z.

As shown in FIG. 2, the laser heating machine 30 irradiates a part of the spirally formed wire 1 with a laser beam L. By irradiating the laser beam L, a heated region 1V having a higher temperature than other parts is formed in the wire 1.

In the example of FIGS. 1 and 2, the laser heating machine 30 includes a laser oscillator 31, an optical fiber 32, and a laser head 33. The laser head 33 includes, for example, a beam spot adjuster.

For the laser oscillator 31, for example, a semiconductor laser that generates the laser beam L can be used. The optical fiber 32 transmits the laser beam L generated by the laser oscillator 31 to the laser head 33. The laser head 33 adjusts the beam shape of the laser light L into a rectangular or circular shape using the above-mentioned beam spot adjuster. As the beam spot adjuster, for example, an optical element such as a beam homogenizer can be used.

The laser heating machine 30 may further include a measuring device 34 that measures the temperature of the heated region 1V. The measuring device 34 includes, for example, a sensor that detects the temperature of the heated portion 1V of the wire 1. The measuring device 34 may be provided on the side of the cutting unit 40 in order to avoid interference with the cutting unit 40. The measuring device 34 may be configured to be moved away from the cutter 41 in conjunction with the operation of the cutter 41 in order to avoid interference with the cutter 41, which will be described later. The measurement results obtained by the measuring device 34 can be used, for example, to control the timing at which the cutting unit 40 cuts the wire 1 .

Note that the measuring device 34 is not an essential component. That is, without using the measuring device 34, various conditions for cutting the wire 1 may be set in advance, and the cutting unit 40 may cut the heated portion 1V based on the conditions.

The laser heating machine 30 may further include a moving stage that causes the laser head 33 to approach and move away from the heating region 1V of the wire 1. The moving stage can be configured by, for example, a linear motion stage or a robot hand. If the working distance of the laser head 33 is set sufficiently long or if interference with the cutting unit 40 can be avoided, there is no need to use a moving stage.

The cutting unit 40 cuts the heated portion 1V of the wire 1, which has a higher temperature after the irradiation of the laser beam L is stopped than before the irradiation with the laser beam. In the example of FIGS. 1 and 2, the cutting unit 40 includes a cutter 41 and a mandrel 42.

The cutter 41 is arranged between the second forming roller 22 and the pitch tool 23 in the circumferential direction Dθ. The cutter 41 has, for example, a sharp cutting blade at its tip that extends in the forming direction Z. The cutter 41 is configured to be movable along the vertical direction Y by a drive mechanism (not shown).

The mandrel 42 is arranged inside the first forming roller 21, the second forming roller 22, and the pitch tool 23. The mandrel 42 has a semicircular shape along the XY plane, for example, as shown in FIG. 2, and extends long in the forming direction Z. The mandrel 42 supports the inner circumferential surface of the spirally formed wire 1 mainly at the end of the arcuate surface in the vertical direction Y.

The control unit 50 controls the transport unit 10, the spiral forming unit 20, the laser heating machine 30, and the cutting unit 40. Such a control unit 50 includes a controller 51.

The controller 51 includes a ROM (Read Only Memory), a CPU (Central Processing Unit), and a RAM (Random Access Memory). The ROM stores a computer program for controlling the conveyance unit 10, the spiral forming unit 20, the laser heating machine 30, and the cutting unit 40. The CPU executes computer programs stored in the ROM. The RAM temporarily stores various data generated as the computer program is executed by the CPU.

Next, a method for manufacturing the coil spring 2 using the coiling machine 100 according to the present embodiment will be described with reference to FIGS. 3 to 13.

FIG. 3 is a flowchart showing the operation of the coiling machine 100. The operations shown in this flowchart are mainly realized by the controller 51 executing a computer program. The manufacturing process of the coil spring 2 by the coiling machine 100 includes a spiral forming process S01, a heating process S02, and a cutting process S03.

In the spiral forming step S01, the wire 1 is formed into a spiral shape. In the heating step S02 after the spiral forming step S01 is completed, a portion of the wire 1 is irradiated with the laser beam L, thereby forming a heated region 1V in the wire 1. The heated portion 1V includes a portion of the wire 1 that is softer than other portions (base material). In the cutting step S03 after the heating step S02 is completed, the heated portion 1V of the wire 1 is cut.

FIG. 4 is a schematic perspective view of a coiling machine 100 showing a specific example of the spiral forming process S01. In the spiral forming step S01, the conveyance unit 10 causes the wire 1 to move straight in the conveyance direction X using the driving roller 11 and the driven roller 12, and guides it to the wire guide 13. The wire 1 led out from the wire guide 13 is bent in the vertical direction Y by the first forming roller 21 and the second forming roller 22, and is formed into an arc shape. The wire 1 formed into an arc shape is guided by a pitch tool 23 so that it is formed into a spiral shape with a predetermined pitch. By such an operation, the spiral wire 1 is gradually extended in the forming direction Z.

FIG. 5 is a schematic perspective view of the coiling machine 100 showing a specific example of the heating step S02. In the heating step S02, the laser heating machine 30 directly applies a laser beam to, for example, a portion of the spirally formed wire 1 located near the end of the mandrel 42 in the vertical direction Y (below the cutter 41). Irradiate L. The energy of this laser beam L heats the base material of the wire 1, and a softened heated region 1V is formed.

When the heating step S02 is executed, the transport of the wire 1 by the transport unit 10 is stopped. The laser heating device 30 is fixedly arranged at a predetermined position, for example, and irradiates the laser beam L toward a part of the wire 1 that is stopped from this position. As another example, when the laser heating machine 30 has the above-mentioned moving stage, the laser heating machine 30 may irradiate the laser beam L after bringing the laser head 33 closer to the wire 1. Further, in the heating step S02, the laser heating device 30 may irradiate the portion of the wire 1 that is sent in the circumferential direction Dθ with the laser beam L without stopping the transport of the wire 1 by the transport unit 10. In this case, the movement of the laser heating device 30 may be controlled so that the irradiation position of the laser beam L moves following the movement of the cutting position due to coiling.

FIG. 6 is a perspective view of the wire 1 showing a first example of a method of heating and softening a part of the wire 1. In this example, the laser heating device 30 irradiates the surface of the wire 1 with laser light L1 in the irradiation direction DL. The laser beam L1 has, for example, a long rectangular beam profile in the width direction of the wire 1. A heated region 1V is formed in and around the irradiation region 1a of the wire 1 irradiated with the laser beam L1.

FIG. 7 is a cross-sectional view of the wire 1 along line VII-VII in FIG. 6. The heating region 1V extends not only around the irradiation area 1a on the surface of the wire 1 but also inside the wire 1. In the example of this figure, the width of the laser beam L1 is smaller than the diameter R of the wire 1. Therefore, most of the laser light L1 is irradiated onto the wire 1.

FIG. 8 is a perspective view of the wire 1 showing a second example of a method of heating and softening a part of the wire 1. In this example, the laser heating device 30 irradiates the surface of the wire 1 with laser light L2 in the irradiation direction DL. The laser beam L2 has, for example, a circular beam profile. A heated region 1V is formed in and around the irradiation region 1a of the wire 1 irradiated with the laser beam L2, as in the first example.

FIG. 9 is a cross-sectional view of the wire 1 taken along line IX-IX in FIG. The heating region 1V extends not only around the irradiation area 1a on the surface of the wire 1 but also inside the wire 1. For example, the diameter of the laser beam L2 is smaller than the diameter R of the wire 1. Therefore, most of the laser light L2 is irradiated onto the wire 1.

The heating region 1V may extend further into the wire 1 than in the examples shown in FIGS. 7 and 9. The shape of the laser beam L emitted by the laser heating machine 30 is not limited to the first example and the second example.

In both the first and second examples, the heating region 1V may include a molten pool in which the base material of the wire 1 is melted by the energy of the laser beam L. The molten pool may spread not only in the irradiated area 1a but also around it.

FIG. 10 is a schematic perspective view of a coiling machine 100 showing a specific example of the cutting process S03. In this embodiment, the cutting step S03 is executed after the irradiation of the laser beam L is stopped. As another example, the cutting step S03 may be performed during irradiation with the laser beam L. In the cutting step S03, the heating portion 1V of the wire 1, which is at a higher temperature than before being irradiated with the laser beam L, is cut by the cutting unit 40. In this way, the coil spring 2 is manufactured.

Specifically, in the cutting step S03, the cutter 41 descends toward the vicinity of the portion of the wire 1 that is supported by the mandrel 42. At this time, the wire 1 is cut by the impact given by the cutter 41.

When the heating region 1V includes a molten pool, the molten pool may solidify after the irradiation of the laser beam L stops and before the cutter 41 operates. Furthermore, after the cutter 41 is operated, when the cutter 41 comes into contact with the surface of the wire 1, the cutter 41 removes the heat from the heated portion 1V, thereby solidifying the molten pool. In this way, by solidifying the molten pool before or during the operation of the cutter 41, it is possible to prevent molten metal from adhering to the cutter 41.

In the cutting step S03, the cutter 41 can also be operated based on the measurement result of the temperature of the heated region 1V by the measuring device 34. That is, after irradiation with the laser beam L, the cutter 41 may operate when the temperature of the heated region 1V falls to a predetermined target temperature. The target temperature may be, for example, a temperature at which the molten base material solidifies. Of course, in the cutting step S03, the heated region 1V may be cut without using the measuring device 34 by predetermining a delay time from the stop of irradiation of the laser beam L to the start of operation of the cutter 41.

The cut coil spring 2 has a first end 61 including a first end surface 61a and a second end 62 including a second end surface 62a. After one coil spring 2 is manufactured, the above-described spiral forming step S01, heating step S02, and cutting step S03 are performed again to manufacture the next coil spring 2. Therefore, both the first terminal 61 and the second terminal 62 are cut through the above-mentioned steps.

The shearing force required to cut the wire 1 decreases as the wire 1 is heated and its temperature increases. Further, even if the wire 1 has not reached its melting point, the shearing force can be reduced. Furthermore, this tendency does not depend on the diameter of the wire 1. As an example, when cutting the wire 1 with the cutter 41, it is preferable that the temperature of at least a portion of the heated portion 1V is 500° C. or higher.

FIG. 11 is a schematic cross-sectional view of the wire 1 irradiated with the laser beam L. Here, it is assumed that the surface of the wire 1 is irradiated with the laser beam L2 having the shape shown in FIG. 8, and a molten pool is formed. O in the figure indicates the center of the irradiation area 1a of the laser beam L on the outer peripheral surface of the wire 1 (see FIGS. 6 and 8). As an example, this irradiation center O corresponds to the position where the peak portion of the highest intensity in the beam profile of the laser light L is irradiated. Moreover, the irradiation center O can also be considered as the center of the molten pool.

As described above, when the wire 1 is irradiated with the laser beam L, the heated region 1V is formed. During or immediately after irradiation with the laser beam L, a molten pool is formed around the irradiation center O. By subsequent cooling, the molten pool solidifies and a quench hardened portion 1C is formed. A heat affected zone 1H (HAZ) is formed around the molten pool, which is not melted but whose characteristics have changed from the base material of the wire 1 due to the heat generated during irradiation with the laser beam L. In this way, the heated portion 1V includes the quench hardened portion 1C and the heat affected zone 1H.

FIG. 11 shows the results of measuring the Vickers hardness [HV] of each of the quench hardened portion 1C, the heat affected zone 1H, and the base material of the wire 1. The quench hardened portion 1C has greater hardness overall than the base material. On the other hand, the heat affected zone 1H has a lower hardness overall than the base material. The hardness of the heat-affected zone 1H gradually increases from the vicinity of the quench-hardened zone 1C toward the base material.

In this way, the distribution of hardness is not uniform even in the heated region 1V. Therefore, it is necessary to appropriately determine the relationship between the positions of the cutter 41 and the mandrel 42 and the irradiation area of the laser beam L.

FIG. 12 is a cross-sectional view showing an example of a suitable positional relationship between the cutter 41, the mandrel 42, and the irradiation area of the laser beam L. In the above-described spiral forming step S01, the wire 1 formed into a spiral shape is sent between the cutter 41 and the mandrel 42. In the feeding direction of the wire 1 (circumferential direction Dθ), a clearance G is provided between the end 41a of the cutter 41 and the end 42a of the mandrel 42. Hereinafter, the center of the clearance G in the circumferential direction Dθ will be referred to as a clearance center C.

In the example of FIG. 12, the clearance center C and the irradiation center O are shifted in the circumferential direction Dθ. Specifically, the irradiation center O is located closer to the cutter 41 (downstream in the circumferential direction Dθ) than the clearance center C.

In the example of FIG. 12, the heating region 1V includes a molten pool 1P that becomes the above-mentioned quench hardened portion 1C after solidification. For example, the melt pool 1P overlaps with the clearance center C. Further, the molten pool 1P overlaps the end portion 41a of the cutter 41 in the vertical direction Y.

On the other hand, the molten pool 1P does not overlap the end 42a of the mandrel 42 in the vertical direction Y. In the example of FIG. 12, the end portion 42a of the mandrel 42 and the portion of the heat affected zone 1H located upstream of the molten pool 1P in the circumferential direction Dθ overlap in the vertical direction Y.

FIG. 13 is a sectional view showing a state in which the wire 1 is cut by lowering the cutter 41 in parallel to the vertical direction Y from the state shown in FIG. As described above, when cutting the wire 1 with the cutter 41, the molten pool 1P is already solidified, or heat is removed by contact with the cutter 41, and the molten pool 1P solidifies. Therefore, a quench hardened portion 1C is formed during cutting. Note that during cutting, a portion of the molten pool 1P may remain inside the heating portion 1V.

When the tip of the cutter 41 impacts the outer circumferential surface of the wire 1 protruding from the end 42a of the mandrel 42, shearing force is applied to the heated region 1V and its surroundings, causing the wire 1 to break. The cutter 41 descends, for example, to the vicinity of the axis of the wire 1 at the maximum. A dent B (recess) by the cutter 41 is formed on the cut wire 1, that is, the coil spring 2. In the example of FIG. 13, the quench-hardened portion 1C and the heat-affected zone 1H overlap with the dent B, but these may be shifted from each other.

As described above, the heat-affected zone 1H is softer than the quench-hardened portion 1C and the base material of the wire 1. Therefore, when the cutter 41 applies an impact to the wire 1, the heat affected zone 1H is likely to break at the heated portion 1V. In particular, if the irradiation center O is shifted toward the cutter 41 side from the clearance center C as shown in FIG. It is possible to apply a load to the wire 1 and break the wire 1 along the corresponding portion.

FIG. 14 is a schematic side view of the coil spring 2 cut from the wire 1 in the manner shown in FIGS. 12 and 13. The coil spring 2 has a first end 61 including a first end surface 61a and a second end 62 including a second end surface 62a.

The first end surface 61a corresponds to the fractured surface of the coil spring 2 cut off from the wire 1 in FIG. The first terminal 61 has a first irradiation mark M1 of the laser beam L and a dent B of the cutter 41. The first irradiation mark M1 includes a quench hardened portion 1C and a heat affected zone 1H (first heat affected zone).

The second end surface 62a corresponds to the fractured surface of the wire 1 left above the mandrel 42 when the coil spring 2 manufactured before this coil spring 2 is cut off. The second terminal 62 has a second irradiation mark M2 of the laser beam L. The second irradiation mark M2 includes a heat affected zone 1H (second heat affected zone). When the wire 1 is cut as shown in FIG. 13, the second irradiation mark M2 does not include the quench hardened portion 1C. However, the second irradiation mark M2 may include, for example, a smaller amount of the quench hardened portion 1C than the first irradiation mark M1.

The heat affected zone 1H included in the first irradiation mark M1 extends over at least a portion of the first end surface 61a. Furthermore, the heat affected zone 1H included in the second irradiation mark M2 extends over at least a portion of the second end surface 62a. On the other hand, the quench hardened portion 1C included in the first irradiation mark M1 does not extend to the first end surface 61a. However, a part of the quench hardened portion 1C may extend to the first end surface 61a. In this case, in the first end surface 61a, it is preferable that the area of the quench hardened portion 1C is smaller than the area of the heat affected zone 1H.

Next, the irradiation conditions of the laser beam L will be explained.
FIG. 15 is a schematic plan view of the surface of the wire 1, which is irradiated with the laser beam L1 having a rectangular beam profile as shown in FIG. 6, as viewed in the irradiation direction DL. In the following description, a direction parallel to the axis of the wire 1 will be referred to as an axial direction DA, and a direction perpendicular to the axial direction DA and the irradiation direction DL will be referred to as a width direction DW of the wire 1.

The dotted area in FIG. 15 corresponds to the irradiation area 1a of the laser beam L1 on the surface of the wire 1. When viewed in the irradiation direction DL, the irradiation area 1a has a rectangular shape having a width W1 in the axial direction DA and a width W2 in the width direction DW. Width W1 is smaller than width W2. That is, in the example of FIG. 15, the irradiation area 1a has an elongated shape in the width direction DW.

FIG. 16 is a diagram for explaining the definition of the irradiation area 1a shown in FIG. 15. FIG. 16 shows a center line CL1 passing through the irradiation center O of the irradiation area 1a and parallel to the axial direction DA, and a center line CL2 passing through the irradiation center O and parallel to the width direction DW. On the surface of the wire 1, the laser beam L1 has an output distribution PW1 along the center line CL1 and an output distribution PW2 along the center line CL2.

In the example of FIG. 16, the output distribution PW1 is a Gaussian type, and the output distribution PW2 is a top hat type. The Gaussian output distribution PW1 has a mountain shape with the output value peaking at the center. The top-hat type output distribution PW2 has a trapezoidal shape in which the peak of the output value extends over a wide range.

In this embodiment, the half-value width in the output distribution PW1 is defined as the width W1, and the half-value width in the output distribution PW2 is defined as the width W2. Note that the half-width of the Gaussian output distribution PW1 corresponds to the width of the output distribution PW1 at a position where the output value is half of the peak PK. Similarly, the half-width of the top-hat type output distribution PW2 corresponds to the width of the output distribution PW2 at the position where the output value is half of the peak. The half-value width of the top-hat type output distribution PW2 can also be said to be the value obtained by adding the bottom length Wb and the top length Wt of the output distribution PW2 and multiplying the sum by 1/2.

FIG. 17 is a schematic plan view of the surface of the wire 1, which is irradiated with the laser beam L2 having a circular beam profile as shown in FIG. 8, as viewed in the irradiation direction DL. In the example of FIG. 17, the irradiation area 1a is a perfect circle with a diameter Ra.

FIG. 18 is a diagram for explaining the definition of the irradiation area 1a shown in FIG. 17. For example, the laser beam L2 has a Gaussian output distribution PW on a line segment passing through the irradiation center O, such as center lines CL1 and CL2, on the surface of the wire 1. The diameter Ra corresponds to the half width of the output distribution PW, that is, the width of the output distribution PW at a position where the output value is half of the peak PK.

Note that the irradiation area 1a of the laser beam L2 may be defined in a rectangular shape represented by a width W1 in the axial direction DA and a width W2 in the width direction DW, similarly to the examples of FIGS. 15 and 16.

The shape of the irradiation area 1a and the output distribution of the laser beams L1 and L2 are not limited to those illustrated using FIGS. 15 to 18. For example, in FIGS. 15 and 16, both output distributions PW1 and PW2 may be top hat type, or both output distributions PW1 and PW2 may be Gaussian type. Furthermore, in the examples of FIGS. 17 and 18, the output distribution PW may be top-hat shaped.

The irradiation area 1a may be defined as an area where the laser beam L is irradiated with an output equal to or more than half the peak value, and its shape is not limited to a rectangular shape or a perfect circle. As another example, the irradiation area 1a may be elliptical. In this case, the long axis and short axis of the irradiation area 1a may be defined by the half width of the output distribution.

FIG. 19 is a table showing irradiation conditions applicable to the laser beam L and Examples 1, 2, and 3. A cutting method using both heating by the laser beam L and the cutting unit 40 as in this embodiment is suitable for cutting a thick wire 1 having a diameter R of 8 mm or more, for example. However, if the wire 1 is too thick, a good cut surface may not be obtained. Therefore, in this embodiment, as an example, it is assumed that the diameter R of the wire 1 is 8 mm or more and 18 mm or less, as shown in the irradiation conditions of FIG.

Considering heating efficiency, it is preferable that the laser beam L is irradiated so as not to protrude the wire 1. Moreover, if the irradiation area 1a of the laser beam L is too small, there is a possibility that the heat-affected zone 1H having a shape suitable for cutting cannot be formed on the wire 1. Therefore, for example, if the irradiation area 1a has a rectangular shape as shown in FIGS. 15 and 16, and the diameter R of the wire 1 is 8 mm or more and 18 mm or less, the width W1 of the irradiation area 1a is set to 2 mm or more and 6 mm or less, and the width It is preferable that W2 be 8 mm or more and 18 mm or less. In the case of such an irradiation size, the irradiation area (width W1 x width W2) is 16 mm ² or more and 108 mm ² .

The output of the laser beam L needs to be determined so that a sufficient heat-affected zone 1H is formed in the wire 1 and the wire 1 is not cut by irradiation with the laser beam L alone. If the output of the laser beam L is small, the irradiation time must be increased in order to form a heat-affected zone 1H sufficient for cutting, but if the irradiation time is too long, the manufacturing efficiency of the coil spring 2 will decrease. Moreover, when the output of the laser beam L is large, the laser heating machine 30 becomes large and the degree of freedom in layout of each part of the coiling machine 100 decreases. Furthermore, the wire 1 may be overheated and the quench hardened portion 1C may become large or spatter may occur.

For example, taking these into consideration, it is preferable that the output of the laser beam L be 500 W or more and 8000 W or less. Further, the output density corresponding to the output of the laser beam L per unit area is preferably 10 W/mm ² or more and 100 W/mm ² or less. It is more preferable that the power density is 31 W/mm ² or more and 74 W/mm ² or less.

Note that the output density is a value obtained by dividing the output of the laser beam L by the area of the irradiation region 1a on the surface of the wire 1 when viewed in the irradiation direction DL. Furthermore, the irradiation region 1a referred to herein is a region defined by the half-width of the output distribution of the laser beam L on the surface of the wire 1, for example, as described using FIG. 16.

In Examples 1, 2, and 3 shown in FIG. 19, the output of the laser beam L is 3000 W, but the irradiation size and irradiation area are different. The irradiation size is 4 mm x 14 mm in Example 1, 3.9 mm x 12.1 mm in Example 2, and 3.8 mm x 15.4 mm in Example 3. Further, the irradiation area was 56 mm ² in Example 1, 47.19 mm ² in Example 2, and 58.52 mm ² in Example 3.

The power density in this case is 53.57 W/mm ² in Example 1, 63.57 W/mm ² in Example 2, and 51.26 W/mm ² in Example 3. These output densities are all 10 W/mm ² or more and 100 W/mm ² or less, as shown in the irradiation conditions of FIG. 19, and further 31 W/mm ² or more and 74 W/mm ² or less.

When manufacturing a coil spring 2 using a coiling machine 100 using a wire 1 with a diameter R of 8 mm or more and 18 mm or less, if the laser beam L under the conditions of Examples 1, 2, and 3 is used in the heating step S02, the amount required for cutting is It was possible to manufacture a coil spring 2 with a small shearing force and a good end shape.

Note that in FIG. 19, it is assumed that the irradiation size is defined by the width W1 and the width W2, but if the irradiation area 1a is circular, the irradiation size may be defined by the radius. In addition, the irradiation size can be determined as appropriate depending on the shape of the irradiation area 1a. Regardless of how the irradiation size is determined, the same effect can be obtained as long as the output density is within the range shown in FIG.

According to the above-described embodiment, the portion of the spirally bent wire 1 that has become hot due to the irradiation with the laser beam L (heated portion 1V) is cut by the cutting unit 40 (cutter 41 and mandrel 42). As a result, the shearing force required for cutting is reduced. Therefore, the wire 1 can be easily cut.

Furthermore, as explained using FIG. 19, by determining the irradiation conditions of the laser beam L such as the output density, it is possible to increase the manufacturing efficiency of the coil spring 2 and obtain a high-quality coil spring 2 with good terminals. Can be done.

The above embodiments do not limit the scope of the present invention to the configuration disclosed in the embodiments. The present invention can be implemented by modifying the configuration disclosed in the embodiment in various ways.

For example, in carrying out the present invention, it goes without saying that the configuration and arrangement of each element included in the coiling machine 100 can be changed in various ways as necessary.

In each embodiment, the coiling machine 100 uses the cutter 41 to cut the heated portion 1V of the wire 1. The coiling machine 100 is not limited to such a configuration, and may cut the heated portion 1V of the wire 1 by cutting using a rotary saw blade.

There are various forms of the coil spring 2 manufactured by the coiling machine 100, and for example, the coil diameter and pitch may change in the axial direction of the coil spring. That is, the coil springs 2 manufactured by the coiling machine 100 include cylindrical coil springs, barrel-shaped coil springs, hourglass-shaped coil springs, tapered coil springs, unequal pitch coil springs, coil springs having negative pitch parts, and the like. , various forms of coil springs may be used.

DESCRIPTION OF SYMBOLS 1... Wire, 1a... Irradiation area, 1V... Heating region, 1P... Molten pool, 1C... Quench hardening part, 1H... Heat affected zone, 2... Coil spring, 10... Conveyance unit, 11... Drive roller, 12... Follower Roller, 13... Wire guide, 20... Spiral forming unit, 21... First forming roller, 22... Second forming roller, 23... Pitch tool, 30... Laser heating machine, 31... Laser oscillator, 32... Optical fiber, 33... Laser head, 34... Measuring device, 40... Cutting unit, 41... Cutter, 42... Mandrel, 50... Control unit, 51... Controller, 61... First terminal, 62... Second terminal, 100... Coiling machine, L, L1 , L2...Laser beam, S01...Spiral forming process, S02...Heating process, S03...Cutting process, M1...First irradiation mark, M2...Second irradiation mark, B...Document mark, X...Transportation direction, Y...Vertical direction , Z... Molding direction, Dθ... Circumferential direction, DL... Irradiation direction.

Claims

a laser heating machine that heats a part of the wire by irradiating the wire into a spiral shape with a laser beam;
a cutting unit that cuts a portion of the wire heated by irradiation with the laser beam;
Equipped with
The output density of the laser beam is 10 W/mm 2 or more and 100 W/mm 2 or less,
coiling machine.
The power density is 31 W/mm 2 or more and 74 W/mm 2 or less,
A coiling machine according to claim 1.
The output density is a value obtained by dividing the output of the laser beam by the area of the irradiation area of the laser beam on the surface of the wire when viewed in the irradiation direction of the laser beam.
A coiling machine according to claim 1.
The irradiation area is an area defined by the half width of the output distribution of the laser beam on the surface of the wire,
A coiling machine according to claim 3.
The irradiation area has an elongated shape in the width direction of the wire,
The coiling machine according to claim 4.
The diameter of the wire is 8 mm or more and 18 mm or less,
The area of the irradiation area is 16 mm 2 or more and 108 mm 2 or less,
The output of the laser beam is 500 W or more and 8000 W or less,
A coiling machine according to any one of claims 3 to 5.
heating a part of the wire by irradiating the wire formed into a spiral shape with a laser beam;
cutting a portion of the wire heated by the laser beam irradiation;
including;
The output density of the laser beam is 10 W/mm 2 or more and 100 W/mm 2 or less,
How to manufacture coil springs.
The power density is 31 W/mm 2 or more and 74 W/mm 2 or less,
The method for manufacturing a coil spring according to claim 7.
The output density is a value obtained by dividing the output of the laser beam by the area of the irradiation area of the laser beam on the surface of the wire when viewed in the irradiation direction of the laser beam.
The method for manufacturing a coil spring according to claim 7.
The irradiation area is an area defined by the half width of the output distribution of the laser beam on the surface of the wire,
A method for manufacturing a coil spring according to claim 9.
The irradiation area has an elongated shape in the width direction of the wire,
The method for manufacturing a coil spring according to claim 10.
The diameter of the wire is 8 mm or more and 18 mm or less,
The area of the irradiation area is 16 mm 2 or more and 108 mm 2 or less,
The output of the laser beam is 500 W or more and 8000 W or less,
A method for manufacturing a coil spring according to any one of claims 9 to 11.